Perhaps one of the oldest tools known to man is the bow and arrow. Over the centuries, a vast number of advancements have been made to bows, arrows, and the tips used on arrows to harvest game. Unlike bullets which cause death by trauma, arrows are tipped with devices known as broadheads that are designed to cut tissue, arteries, veins, etc. to cause death from hemorrhaging.
The predecessor to the modern day broadhead comprised a head that was knapped or otherwise fashioned from flint or other materials that would tend to break and form sharp edges. Those heads were generally formed with two sharp edges and were then lashed onto an end of a wooden arrow shaft. Today, broadheads are made from metal and may have several sharpened cutting edges. In some modern day broadheads, the cutting edges are formed on portions of the broadhead body. Other modern day broadheads employ replaceable blades that may be readily replaced after they become dull.
Because broadheads are designed to kill by hemorrhaging, it is desirable for the cutting edges to be as large as possible. However, with modern day high speed bows, it is believed that large fixed blade broadheads may tend to undesirably steer the front end of the arrow and cause it to plane off target. To address such problems caused by fixed blade broadheads, expandable or “open on impact” broadheads were developed. In general, the blades in expandable broadheads are movable from a first position adjacent to the shaft to a second open position wherein the cutting edges thereof are positioned to cut tissue upon impact with the animal or target. When the blades are in the first position, they do not present surfaces that are prone to steer the arrow.
A variety of different expandable broadheads are known. Examples of such expandable broadheads are disclosed in U.S. Pat. No. 6,322,464 to Sestak, U.S. Pat. No. 6,517,454 to Barrie et al., U.S. Pat. No. 6,554,727 to Armstrong et al., U.S. Pat. No. 6,595,881 to Grace, Jr. et al., U.S. Pat. No. 6,669,586 to Barrie et al., U.S. Pat. No. 6,910,979 to Barrie et al., and U.S. Pat. No. 7,226,375 to Sanford, the disclosures of which are each herein incorporated by reference in their respective entireties. While such broadheads effectively addressed the steering problems encountered when using fixed blade broadheads, some hunters are reluctant to use such broadheads that are fashioned to provide large cutting diameters because it is believed that the those broadheads would have difficulty penetrating through areas where bone or other similar material is present.
Thus, there is a need for an expandable or open on impact broadhead that presents a large cutting diameter when the broadhead encounters normal fleshy tissues, yet provides a means for the blades to shorten upon contact with more difficult to penetrate areas and more rigid material such as bone.